Tun Seng Herng

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Coexistence of polarization and resistance-switching characteristics in single compounds has been long inspired scientific and technological interests. Here, we report the non-volatile resistance change in noncentrosymmetric compounds investigated by using defect nanotechnology and contact engineering. Using a noncentrosymmetric material of ZnO as example,(More)
The ferromagnetism in many carbon nanostructures is attributed to carbon dangling bonds or vacancies. This provides opportunities to develop new functional materials, such as molecular and polymeric ferromagnets and organic spintronic materials, without magnetic elements (for example, 3d and 4f metals). Here we report the observation of room temperature(More)
We report direct evidence of room-temperature ferromagnetic ordering in O-deficient ZnO:Cu films by using soft x-ray magnetic circular dichroism and x-ray absorption. Our measurements have revealed unambiguously two distinct features of Cu atoms associated with (i) magnetically ordered Cu ions present only in the oxygen-deficient samples and (ii)(More)
A networked spin cage comprising infinite Co(II)6L4 cages arrays (where Co = Co(NCS)2 and L = 1,3,5-tri-(4-pyridyl)-verdazal radical) is synthesized and found to exhibit tunable magnetic and electrochemical properties via inclusion of guests. SQUID investigation reveals the coexistence of ferromagnetic and anti-ferromagnetic interactions between the Co(II)(More)
While the chemistry of open-shell singlet diradicaloids has been successfully developed in recent years, the synthesis of π-conjugated systems with poly-radical characters (i.e., beyond diradical) in the singlet ground state has been mostly unsuccessful. In this study, we report the synthesis and isolation of two fully fused macrocycles containing four(More)
We theoretically predicted that acetylene-bridged benzo[1,2-c;4,5-c']bis[1,2,5]thiadiazole (BBT) oligomers would show a quick increase of diradical character with extension of chain length. To validate the hypothesis, six stable BBT-based diradicaloids were synthesized and fully characterized by X-ray crystallographic analysis and various spectroscopic(More)
Organic π-extended radicals display unique electronic structures and could be used as promising functional materials. However, design and synthesis of stable radicals are challenging for chemists due to their intrinsic high reactivity. In this work, we synthesized a stable N-annulated perylene bridged bisphenoxyl diradicaloid, and its complex with Lewis(More)
The bipolar charge phenomenon in Cu and Co co-doped zinc oxide (ZnO) film samples has been studied using scanning probe microscopy (SPM) techniques. Those ZnO samples are made using a pulsed laser deposition (PLD) technique. It is found that the addition of Cu and Co dopants suppresses the electron density in ZnO and causes a significant change in the work(More)